Remote-control manipulator



Nov. 23, 1965 A. AINSWORTH REMOTE-CONTROL MANIPULATOR 11 Sheets-Sheet 1Filed May 1, 1965 Nov. 23, 1965 A. AINSWORTH REMOTE-CONTROL MANIPULATOR11 Sheets-Sheet 2 Filed May 1, 1963 Nov. 23, 1965 A. AINSWORTH 3,219,200

REMOTE-CONTROL MANIPULATOR Filed May 1, 1963 ll Sheets-Sheet 5 Nov. 23,1965 A. AINSWORTH REMOTE-CONTROL MANIPULATOR 11 Sheets-Sheet 4 Filed May1, 1963 Nov. 23, 1965 A. AINSWORTH REMOTE-CONTROL MANIPULATOR llSheets-Sheet 5 Filed May 1, 1963 Nov. 23, 1965 A. AINSWORTHREMOTE-CONTROL MANIPULATOR 11 Sheets-Sheet 6 Filed May 1, 1963 ,5?! imwlam Nov. 23, 1965 A. AINSWORTH REMOTE-CONTROL MANIPULATOR llSheets-Sheet 7 Filed May 1, 1963 Nov. 23, 1965 A. AINSWORTHREMOTE-CONTROL MANIPULATOR 11 Sheets-Sheet 9 Filed May 1, 1963 Nov. 23,1965 Filed May 1, 1963 A. AINSWORTH REMOTE-CONTROL MANIPULATOR 1],Sheets-Sheet 10 Nov. 23, 1965 A. AINSWORTH 3,219,200

REMOTE-CONTROL MANIPULATOR Filed May 1, 1963 11 Sheets-Sheet 11 \g lllllI as" AS E4 United States Patent 3,219,200 REMOTE-CONTROL MANIPULATORAlan Ainsworth, Thurso, Caithness, Scotland, assignor to United KingdomAtomic Energy Authority, London, England Filed May 1, 1963, Ser. No.277,202 Claims priority, application Great Britain, May 7, 1962, 17,441,17,442 2 Claims. (Cl. 214-1) This invention relates to remote-controlmaniupulators whereby objects, such as radioactive materials, can bemanipulated in a shielded cabinet by an operator standing outside thecabinet and viewing the object through a window in the cabinetshielding.

A remote-control manipulator has a master arm carrying a handgripoutside the shielded cabinet and a slave arm carrying a work handlerwithin the cabinet. Since it is necessary for the operator to be able towatch the handler, the working area within the cabinet is limited by thewidth of the shielded window. Any increase in this area must be gained,therefore, by extending the reach of the manipulator in a plane normalto the shielded window. In known manipulators having master and slavearms linked to pivot with respect to a horizontal beam extending betweenthem, the reach of the manipulator has been increased by making themaster and slave arms extensible. In these manipulators the slave armcan be caused to pivot away from the window with respect to the beamindependently of the master arm. However, in order to bring the workhandler down to its original height, the operator must cause extensionof the slave arm by extending the master arm. It then becomes diflicultfor the operator to control the manipulator by means of the handgripwhich is abnormally low while simultaneously viewing the handler throughthe window. Thus an increase in the reach of this manipulator is gainedat the expense of the ease with which the operator can control thereactor.

Accordingly, the present invention provides a remotecontrol manipulatorcomprising a transverse extensible beam, master and slave arms pivotallyconnected to the beam at shoulder joints spaced axially of the beam, ahandgrip carried by the master arm, a work handler carried by the slavearm, means interconnecting the handgrip and the handler to causemovements of the handgrip to be reproduced by the handler, and means forcausing extension of the beam to vary the axial displacement between theshoulder joints and thus to cause transverse displacement of the handlerrelative to the handgrip.

In one embodiment of the invention the transverse beam comprises twotubular beam casings one of which is telescopically slidable within theother and a fluid pressure operated ram is connected between the twocasings to cause relative axial displacement of the casings.

A manipulator embodying the invention will now be described by way ofexample with reference to the accompanying drawings in which:

FIGURE 1 is a perspective overall view of the manipulator,

FIGURE 2 is a side View of the manipulator master wrist unit,

FIGURE 3 is a section on line 33 of FIGURE 2,

FIGURE 4 is a front elevation of the lower part of the master arm,

FIGURE 5 is a section on line 55 of FIGURE 4,

FIGURE 6 is a section on line 6-6 of FIGURE 5,

FIGURE 7 is a section on line 77 of FIGURE 4 showing forearmcompensating mechanism,

FIGURE 8 is a plan view of a detail of FIGURE 7,

FIGURES 9 and 10 are part section views of the lower and upper parts ofthe master arm,

FIGURE 11 is a section on line 1111 of FIGURE 10,

FIGURE 12 is a view along arrow 12 with part of the master arm casingbroken away,

FIGURE 13 is a sectional view of the master shoulder joint viewed fromunderneath,

FIGURE 14 is a part sectional view of the manipulator beam,

FIGURE 15 is a section on line 1515 of FIGURE 14,

FIGURE 16 is a section on line 16-16 of FIGURE 14,

FIGURE 17 is a section on line 17-17 of FIGURE 14, and FIGURE 18 is asection on line 18-18 of FIG- URE 14.

General assembly In FIGURE 1 there is shown a perspective view of amanipulator embodying the invention. The manipulator is shown mounted inthe wall 11 of a cabinet which is shielded so that radioactive materialscan be handled by means of the manipulator by an operator outside thecabinet who views the materials through a shielded window 12. In FIGURE1 the wall is shown broken away so that the master arm of themanipulator outside the cabinet and the slave arm within the cabinet canbe seen.

The manipulator comprises a socket 13 in the wall through which ispassed a beam 14 connected at each end by shoulder joints 15 to upperarms 16 of the master and slave arms. A forearm 17 telescopicallymounted within each upper arm terminates at a wrist unit 18. Within theshielded cabinet the slave wrist unit supports a pair of jaws 21;outside the shielded cabinet the master wrist unit supports a handgrip22 which is squeezed to close the jaws. There are six basic degrees ofmovement in the manipulator which are controlled by movement of thehand-grip and are reproduced as movements of the jaws within thecabinet. The six degrees of movement are:

Rotation of the jaws or handgrip about the wrist units (arrow 23)Flexure at the wrist units (arrow 24) Rotation of the wrist units aboutthe forearms (arrow Swing of the arms about the shoulder joints (arrow26) Rotation of the beam in its socket (arrow 27) Telescopic movement ofthe forearms in the upper arms.

These six movements are transmitted from the master arm to the slave armin the following manner. Rotation of the beam in its socket istransmitted directly from the master shoulder joint to the slaveshoulder joint. Swing of the master arm about the master shoulder jointactuates a servo-valve 31 which initiates servo-assistance of the masterarm movement and causes movement of the slave arm by movement of therams 29. Similarly telescopic movement of the master forearm into themaster upper arm actuates a servo-valve 34 which initiatesservoassistance of the master forearm movement and causes telescopicmovement of the slave forearm by means of rams 33. Finally the threeremaining movements at the master wrist unit are converted by gearinginto relative movement of three rods (to be described hereinafter) whichextend along the arms and the beam to similar gearing at the slave wristunit; thus these three movements are transmitted by direct mechanicallinkages. Compensating mechanisms (to be described hereinafter) areprovided within the forearms and at the shoulder joints to counteractinterference between the relative movements of the three rods.

The six movements are preferably all servo-assisted. As described above,hydraulic rams 29 and 33, with associated servo-valves 31 and 34, assistswing and telescopic movement of the master arm. Similarly a hydraulicram 32, with a servo-valve (not shown in FIG- URE 1), assists rotationof the beam in its socket. If desired, a set of hydraulic motors 24clustered around the beam 14 may be linked to the three connecting rodsto assist rotation of the jaws or handgrip about the wrist units,fiexure at the wrist units and rotation of the wrist units about theforearms.

Wrist units, handgrip and jaw As shown in FIGURE 2, which is an enlargedside view of the handgrip and part of the wrist unit, the handgrip 22'is constituted by two pivoted handles 35' carried by a bush, 36 on a.shaft 37 which is pivotally mounted in a bracket 38 forming part of themaster wrist unit. Within the shaft 37 there is a hydraulic ram (notshown) actuated by means of the handles. This forms part of a circuit bywhich hydraulic power is supplied to a similar ram in the slave wristunit. At the slave wrist unit the handles are replaced by the jaws 21which can be opened andclosed by the ram in the wristunit. Provision ismade for limiting the maximum pressure applied by the jaws when maximumpressure is applied at the handgrip; three ranges of clamping pressure.are provided, namely pressure appropriate to loads at the slave jaws of0. to lbs, 10 to 3.01bs., and 30 to 50 lbs.

The. lower part of the master wrist unit is shown in detail in FIGURE 3,which is a sectional view through part of FIGURE 2. Two lugs 39 integralwith the bracket 38 carry pivot pins 41 provided with bushes 42journalled in trunnions 43. Races of radial needle bearings areinterposed between the lugs and the trunnions and between the lugs andthe pivot pins. The shaft 37 journalled in the bracket 38 carries at itshead a bevel gear 44 meshing with two opposed bevel gears 45 mounted forrotation one on the bush of each pivot pin 41. A toothed wheel 46 issecured to. each bevel gear 45 by a pin 47 and each wheel 46 meshes withone of two pinions, 48a, 48b mounted on spindles 49a, 49b, journalled inthe cross-piece of the trunnions 43. Needle bearings are interposedbetween the bevel 44 and the bracket and between the toothed wheels, 46and the trunnions.

In operation, rotation of the handgrip about the wrist unit causesrotation of the. bevel gear 44, opposed rotation of the bevel gears. 45and thus. opposed rotation of the pinions 48a, 48b and the spindles 49a,49b. Flexure at the. wrist unit of the handgrip about the pivot pins onthe other hand, cause-s similar rotation of, the bevel gears 45, the.pinions 48a, 48b and the spindles 49a, 49b. Any combination of these twomovements i transmitted by appropriate rotation of the two spindles 49a,49b. It will be appreciated that similar gearing in the slave wrist unittranslates relative rotation of the two spindles into appropriatemovements of the jaws.

The trunnions 43 are bolted to a wrist casing 51 (FIG- URE 4) supportedat the lower end of the forearm 17 by adilferential casing 52- bolted toa forearm casing 53 which is bolted to the forearm itself. The wristcasing 51 is rotatable with respect to the differential casing, abearing race ring 54 being interposed between the two casings.

A bearing plate 55' (FIGURES 4 and 5) bolted to the trunnions 43-carries a clamp 56 by which a spindle 57 is secured to the wrist casing51. The wrist casing 51 houses centralising gears (FIGURES 5 and 6)comprising pinions 58a, 58b on the spindles 49a, 49b, engaging splineson wrist rods 59a, 59b mounted concentrically around the spindle 57 bymeans of needle bearings, the inner wrist rod 59a extending beyond outerwrist rod 59b for this purpose. In operation, the centralising gearsconvert rotary movements of the spindles 49a, 49b into rotary movementsof the rods 59a, 59b. Bearings 61 (FIGURE 6) carried by the bearing racering 54 case rotation of the wrist casing 51 with respect to theforearm. Such rotation is indicated by rotation of the spindle 57relative to the forearm. Thus the three angular wrist movements aretransmitted by'rotational movements of the spindle 57 and the concentricWrist rods 59a, 5% relative to each other and to the forearm 17. Withinthe shielded cabinet similar centralising gears perform the samefunction for the slave wrist unit.

Forearm compensating mechanism Forearm compensating mechanism (FIGURES 7and 8) is housed in the differential casing 52 to counteractinterference between the relative rotations of the forearm, the wristrods and the central pindle 57. Without such compensation a simplerotation of the wrist unit with respect to the forearm would result inrelative movement between the wrist rods and the spindle 57. Thisrelative movement would cause flexure of the wrist unit. Similarcompensating mechanism is provided in the differential casing of theslave forearm.

The spindle 57 extends upwardly through the compensating mechanism andis unaffected by it. Surrounding the spindle the inner concentric wristrod 59a, which is rotatable on needle bearings and supported by thrustbearings, is terminated by an inner ring bevel 62a. Similarly, the outerconcentric wrist rod 59b, which is rotatable on needle bearings andsupported by thrust bearings, is terminated by a central ring bevel 62b.Finally, a cylindrical shell 63 bolted to the Wrist casing 51 isterminated by an outer ring bevel 62c. Thrust bearing carried by thebearing race ring 54, the shell 63 and the outer wrist rod 69b supportthe wrist unit so that it is rotatable with respect to the forearm.Needle bearings are interposed between the concentric members of thecompensating mechanism. The differential casing 52, being bolted to thewrist casing, rotates with the spindle 57.

The ring bevels 62a, 62b and 620 lie in the same plane. Above them, aspider 64 is mounted for free rotation on the spindle 57 being supportedby a thrust bearing carried by the inner wrist rod 59a. The spider 64,which is shown in plan in FIGURE 8, has a hub with a central bore toreceive the spindle 57 and three generally radial webs to support athickened rim. Between the rim and the hub, three sub shafts 65 eachcarry three bevel gear 66 which are free to rotate on the stub shafts.When the spider is in position the sets of three. bevel gears 66 meshwith the three ring bevels 62a, 62b and 620.

The sets of three bevel gears, 66. also mesh with three upper ringbevels 67a, 67b and 670. The outer ring bevel 67c of these three isnon-rotatable, being clamped between the differential casing 52' and theforearm casing 53 to which it is bolted. The central and inner ringbevels 67a and 67b are carried at the lower ends of upper concentricwrist rods 68a and 68b corresponding to lower wrist rods 59a and 59b.Thrust bearings and needle bearings are provided for the upper wristrods as for the lower wrist rods.

The operation of the forearm compensating mechanism is now describedwith regard to the three rotary movements to be transmitted by the wristrods and the central spindle. Relative rotation of the lower wrist rods59a, 59b. is caused by rotation of the handgrip about the wrist unit.This relative rotation is transmitted by the central and inner bevelgears 66 directly to the upper wrist rods 68a, 68b without rotation ofthe spider about the spindle 57. Although the relative rotation of theupper wrist rods isv in a direction opposite to that of the lower wristrods, this inversion is immaterial since it is cancelled by a similarinversion in the compensating mechanism of the slave forearm. Relativerotation of the wrist rods does not include a component of rotationrelative to the central spindle so no compensation is necessary for thismovement.

Relative rotation of the central spindle 57 is caused by two movements,interference between which is counteracted by the compensatingmechanism. These two movements are flexure at the wrist unit causingrelative rotation between the central spindle and the two wrist rods androtation of the wrist unit with respect to the forearm causing relativerotation between the central spindle and the forearm or the differentialcasing 52 secured thereto. The distinction between these two movementsis that in the former there is no relative rotation between the centralspindle and the casing 52 whereas in the latter there is. Accordingly,the shell 63 is constituted as a control element indicative of thepresence or absence of relative movement between the spindle and thecasing 52. The shell is rigidly secured to the wrist casing 51 andindirectly, therefore, to the central spindle so that, when there is norelative rotation between the shell and the casing 52, the spider 64 isheld stationary by the outer ring bevels 62c and 670. With the spiderstationary, relative rotation of the lower wrist rods and the centralspindle is transmitted directly to the upper wrist rods by the bevelsgears 66. On the other hand, when relative rotation of the shell and thecasing 52 is caused by rotation of the wrist unit with respect to theforearm, the spider is caused to rotate at half the speed of relativerotation and in its turn causes the upper wrist rods 68a, 68b to rotatewith respect to the lower wrist rods which are held stationary by theoperator. The effect of the compensating movement applied by the spideris that the upper wrist rods remain stationary with respect to thecentral spindle.

It is to be understood that in operation of the manipulator the threemovements just described are often transmitted stimultaneously throughthe compensating mechanism. The movements have been described separatelyfor the purpose of simplicity. Furthermore it is to be understood thatthe slave forearm is provided with identical mechanism.

Forearm and upper arm The forearm 17, to the lower end of which isbolted the forearm casing 53, is cylindrical and is telescopicallymounted in a cylindrical upper arm 16 (Figures 9, 10, 11). Lugs 69carried by the upper arm 16 and the forearm casing 53 provide anchoragesfor the rams 29 and 33 (which are not shown). To guide the telescopicmovement of the forearm 17, it is provided with diametrically opposedribs 71 running between rollers 72 carried by the upper arm; similarlythe upper arm has diametrically opposed internal ribs 73 running betweenrollers 74 carried by the forearm. At its upper end the upper armcarries brackets 75 which are pivoted to the shoulder joint. It is to beunderstood that the master and slave forearms and upper arms areidentical.

Within the forearm casing 53 decentralising gears (not shown), which aresimilar to the centralising gears within the wrist casing 51, convertrotary movements of the concentric spindle 57 and the upper wrist rods68a, 68b relative to each other and to the differential casing 52 intorotary movements of three tubular connectors 76a, 76b, 76c (of whichonly two connectors 76a and 760 are visible in FIGURE 9). The upper endsof the three connectors 76a, 76b and 760, are of square section and arekeyed into three lower drive tubes 77a, 77b and 770 which form part oftelescopic drive tubing extending through the forearm and upper arm.Upper drive tubes 78a, 78b and 78c are slidable within the lower drivetubes. Housed in a chamber 79 (FIGURES and 12) are displacement gearswhich take the drive from one upper drive tube 780 to a displaced drivetube 78d which is aligned with the other drive tubes 78a and 78b.

Shoulder joints The master shoulder joint (FIGURE 13) incorporates apivot pin 81 journalled in brackets 75 carried at the top of the upperarm 16 and brackets 82 carried at one end of the beam 14 so that themaster arm can be swung about the joint. The brackets 82 are bolteddirectly to the beam and are joined by a web which closes the end of thebeam. The brackets 82 are bolted directly to the upper arm and arejoined by a similar web 84. Cotter pins 85 key the pivot pin 81 to thebrackets 75. The drive tubes 78a, 78b and 780 project through the web 84in which they are journalled and are provided at the ends with pinions86a, 86b and 860 respectively. Similarly drive tubes 87a, 87b and 870extend through the beam 14, project through the web 83 in which they arejournalled, and are provided at their ends with pinions 88a, 88b and880. Between the two webs, and embraced by the brackets 75 and 82, thereis gearing which interconnects the drive tubes 78a, 78b, and 78c and thedrive tubes 87a, 87b and 870 respectively and which constitutes acompensating mechanism to prevent interference with the transmissionbetween the drive tubes by a swinging move ment of the master arm aboutthe shoulder joint.

The gearing in the shoulder joint incorporates three parallel trains ofepicyclic gears interconnecting the three pairs of drive tubes. Thus,gearing interconnecting drive tubes 78a and 87a incorporates a sun gear89a, planetary gears 91a and an annular gear 92a; gearinginterconnecting drive tubes 78b and 87b incorporates a sun gear 89b,planetary gears 91b and an annular gear 92b; and gearing interconnectingdrive tubes 78d and 870 incorporates a sun gear 890, planetary gears 91cand an annular gear 92c. In each case drive is transmitted from the sungear to the annular gear and compensation is applied, when necessary, bymovement of the carriers on which the planetary gears are mounted.

The sun gears 89a, 89b, 890 are mounted for free rotation on the pivotpin 81; each is formed with a toothed flange 93a, 93b, 930 which mesheswith its associated pinion 86a, 86b or 860 respectively. Furthermore,each sun gear has a shaft portion on which is mounted, for freerotation, the corresponding annular gear 92a, 92b or 920. Pinned to eachannular gear is a ring bevel 94a, 94b or 940 which meshes with itsassociated pinion 88a, 88b, or 880. Thus the drive tube 78a isinterconnected with the drive tube 87a by the following train of gears:pinion 86a, toothed flange 93a, sun gear 89a, planetary gears 91a,annular gear 92a, ring bevel 94a and pinion 88a. Similar trains of gearsinterconnect drive tubes 78b and 78d with drive tubes 87b and 870.

A planetary gear carrier is formed by two wheels 95 and 96 joined attheir peripheries by a web 97; the wheels 95 and 96 and the web 97 areformed as an integral casting. The web extends only partly around theperiphery of the wheels so that it does not prevent the master arm fromhinging about the joint through an angle of from a horizontal positiondownwardly. The carrier is mounted, for free rotation, on the pivot pin81. The carrier wheel 96 is formed with an axial rib on which is mountedan annular plate 98a. Carried by the carrier wheel 96 in gaps in the ribare stub shafts 99a which are supported by the annular plate 98a and onwhich are mounted, for free rotation, the planetary gears 91a. Thecarrier wheel 95 carries in a similar manner a set of stub shafts on oneside for the planetary gears 91b and a second set of stub shafts on theother side for the planetary gears 91c.

Compensating movement is applied to the carrier by means of epicyclicgearing incorporating a sun gear 101 mounted on the pivot pin 81 towhich it is splined so that it rotates with the pin, planetary gears 102mounted on the stub shafts 99a carried by the carrier wheel 96, and anannular gear 103 rigidly secured to the cap 84 by a bracket 104 boltedthereto. When the master arm is swung about the shoulder joint relativerotation occurs between the sun gear 101 and the annular gear 103 whichcauses a compensating movement to be applied through the planetary gears102 to the carrier. By means of planetary gears 91a, 91b, 91c thecompensating movement of the carrier introduces a compensation into thegear trains interconnecting the drive tubes 78a, 78b and 78d and thedrive tubes 87a, 87b and 870. The four parallel trains of epicyclicgears being mechanically identical, the effect of the compensatingmovement is that, if relative movement between the sun gears 89a, and89b, 89c and the pivot pin, while the master arm is swung, is preventedby the operator holding the handgrip steady, no rotary movement isapplied to the annular gears 92a, 92b and 920 and consequently the drivetubes 78a, 87b and 87c in the beam.

The slave shoulder joint is similar to the master shoulder joint in allrespects save that the pinions driving the sun gears are mounted ondrive tubes in the beam and the pinions driven by the annular gears aremounted on drive tubes in the slave arms. This inversion is aconsequence of the need to transmit drive through the shoulder jointfrom the sun to the annular wheels.

For simplicity no direct reference has been made to the bearingsprovided in the shoulder joints; their disposition can be seen in FIGURE13.

Beam, socket and pressure-tight seal The beam 14 (FIGURE 14) comprisesan outer beam casing 141 and an inner casing 142 telescopically slidablein the outer casing. A socket 13 in the wall 11 is provided with a liner104 in which the outer beam casing is rotatable. At the outer end of thesocket, that is to say the end outside the shielded cabinet, a plate 105(FIGURES 14 and carries brackets 106 in which are mounted rollers 107 bywhich the outer casing is supported. To restrain axial movement of theouter casing, a bracket 108 provides a mounting for two rollers 109which grip a guide 11 projecting radially of the outer casing 141. Theouter casing is similarly mounted at its inner end on rollers 112carried by brackets 113 (FIG- URES 14 and 17).

Within the outer casing 141, the inner casing is slidable and rotatableon balls 114 at its outer end (FIG- URES 14 and 16) and balls 115 at itsinner end (FIG- URES 14 and The halls 114 are seated in the casing 142and the balls 115 are seated in brackets 116 carried by a cylindricalpressure-tight casing 117. A hydraulic ram 123 is secured to a partition(not shown) which traverses the outer beam casing 141 and has a ram rod124 secured to a partition 125 transverse the inner beam casing 142.Thus the ram is connected between the two casings and the inner casingis movable telescopically within the outer casing by means of the mm. Inthis manner the master and slave shoulder joints at each end of the beamare movable axially of the beam to cause transverse displacement of thehandler relative to the handgrip.

Relative rotation between the inner and outer casings is controlled by apinion 150 (FIGURE 14) carried by the outer casing which meshes with atoothed quadrant 151 formed in the parition 1 carried at the inner endof the inner casing. The pinion is mounted on a telescopic spindle 152which extends axially of the outer casing to a hydraulic motor withinthe beam by which the spindle is rotatable. Fornormal operation of themanipulator the inner and outer casings are locked against relativerotation by means of the pinion and the toothed quardrant. There areoccasions, however, when it is desirable to displace the slave armrelative to the master arm in a plane parallel to the cabinet wall; suchlateral displacement of the slave arm is effected by rotation of thepinion to cause slight relative rotation of the inner and outer casingsto a maximum, for example, of 15 degrees each way.

Extending through the outer and inner beam casings 141 and 142 betweenthe master shoulder joint and the slave shoulder joint are drive tubes,87a, 87b and 870 (of which only- 87c is visible in FIGURE 20). Thesedrive tubes are splined so as to be telescopic in a manner similar tothe drive tubes in the master and slave arms. Furthermore, these drivetubes are provided with universal joints so that they skew to acceptslight relative rotation of the beam casings. As stated above, rotarydrive transmitted through the drive tubes 87a, 87b and 870 may beservo-assisted by hydraulic motors 24 (FIGURE 1).

For the purpose of sealing the manipulator into the cabinet thepressure-tight casing 117 is bolted to a bearing plate 118 at the innerend of the socket and is closed by an end plate 119 having an aperturein which the inner beam is slidable. A packing ring 121 carried by theend plate 119 makes pressure-tight contact with the outer surface of theinner beam casing. A similar pressure-tight casing is provided at theouter end of the beam; this casing is shown broken away in FIGURE 14.When the manipulator is used with alpha-active materials in the shieldedcabinet, the space within the cabinet is maintained at a reduced gaspressure whilst the space Within the pressure-tight casings 117 and 120and within the beam is pressurised with an inert gas, such as nitrogenor argon, leakage through the inner casing 142 being prevented by apartition 130. In the event of any leakage through the seal at the innerend of the socket, the inert gas under pressure escapes into the cabinetthus preventing escape of alpha-particles from the cabinet. The pressureof the inert gas in the casing 117 is registered on a gauge 122 (FIGURE1). Any leakage is indicated by a drop in the pressure registered.

I claim:

1. A remote-control manipulator comprising two tubular beam casingswhich are axially slidable and rotatable relative to each other, the twocasings defining a transverse extensible beam, shoulder joints atopposed ends of the beam, a master arm and a slave arm pivotallyconnected to the beam at the respective shoulder joints, a hand gripcarried by the master arm, a work handler carried by the slave arm, linkmeans between the hand grip and the work handler including telescopicrotary connecting rods extending axia'lly of the beam between theshoulder joints, means to cause relative rotation of the two beamcasings to permit lateral displacement of the slave arm relative to themaster arm, and means to cause relative axial displacement of the twobeam casings thereby to cause transverse displacement of the handlerrelative to the hand grip.

2. A remote-control manipulator comprising two tubular beam casingswhich are axially slidable and rotatable relative to each other, the twocasings defining a transverse extensible 'be am, shoulder joints atopposed ends of the beam, a master arm and a slave arm pivotallyconnected to the beam at the respective shoulder joints, a hand gripcarried by the master arm, a work handler carried by the slave arm, linkmeans between the handgrip and the work handler including telescopicrotary connecting rods extending axially of the beam between theshoulder joints, universal joints in the connecting rods to enable therods to skew during relative rotation of the two beam casings, means tocause relative rotation of the two beam casings to permit lateraldisplacement of the slave arm relative to the master arm, and means tocause relative axial displacement of the two beam casings thereby tocause transverse displacement of the handler relative to the hand grip.

References Cited by the Examiner UNITED STATES PATENTS 2,695,715 11/1954Goertze et al. 2,888,154 5/1959 Ielatis et al.

H GO O. S HULZ, Primary Ex min n

1. A REMOTE-CONTROL MANIPULATOR COMPRISING TWO TUBULAR BEAM CASINGSWHICH ARE AXIALLY SLIDABLE AND ROTATABLE RELATIVE TO EACH OTHER, THE TWOCASINGS DEFINING A TRANSVERSE EXTENSIBLE BEAM, SHOULDER JOINTS ATOPPOSED ENDS OF THE BEAM, A MASTER ARM AND A SLAVE ARM PIVOTALLYCONNECTED TO THE BEAM AT THE RESPECTIVE SHOULDER JOINTS, A HAND GRIPCARRIED BY THE MASTER ARM, A WORK HANDLER CARRIED BY THE SLAVE ARM, LINKMEANS BETWEEN THE HAND GRIP AND THE WORK HANDLER INCLUDING TELESCOPICROTARY CONNECTING RODS EXTENDING AXIALLY OF THE BEAM BETWEEN